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  3. What produces a waterproof super glue, acts like a vacuum cleaner, and even teaches scientists about gene repair? The humble lit

What produces a waterproof super glue, acts like a vacuum cleaner, and even teaches scientists about gene repair? The humble lit

admin2013-06-02  87
问题    What produces a waterproof super glue, acts like a vacuum cleaner, and even teaches scientists about gene repair? The humble little shellfish known as the mussel (贻贝).
   Mussels are found worldwide. Some live in the sea. Others inhabit freshwater streams and lakes. When you try to move a mussel from a rock, you will discover what an incredibly firm grip it has-a necessity if the mussel is to resist the sharp grab of a hungry seabird or the pounding waves of the sea. How does it manage to cling so tight’? When it chooses a place to set up home, it pokes its tongue-shaped foot out of its shell and presses it against a solid surface. Special glands give off a fluid mixture of proteins into a channel that runs the length of the foot. The liquid quickly hardens into a fine, elastic thread about an inch long. Then a tiny pad-like structure at the end of this thread gives off some natural glue-like substance, the mussel lifts its foot, and anchor line number one is complete. These strategically placed threads form a bundle, which ties the mussel to its new home in much the same way that ropes hold down a tent. The whole procedure takes only three or four minutes.
   Imagine having a very strong glue that is non-toxic and so flexible that it can penetrate the tiniest holes and comers, sticking to any surface, even under water. Shipbuilders would welcome it for repairing vessels without the expense of dry-docking them. Auto-body workers would like a really waterproof paint that keeps the rust out. Surgeons would value a safe glue to join broken bones and to close wounds... The list of possible uses appears endless.
   However, scientists are not thinking of using the mussels themselves to produce this super glue. It would take some 10 000 shellfish to make just one gram of glue. So collecting enough mussels to supply the world’s demand for super glue would wipe out the mussel population, many species of which are already endangered. Instead, American researchers have isolated and cloned the genes for five mussel glue proteins, and they are about to mass-produce them in the laboratory. However, the mussel is still one jump ahead. Only the mussel instinctively knows the exact blend of proteins needed for each kind of surface. Molecular biologist Frank Roberto has asked admiringly:" how are you ever going to imitate that?"
选项 A、seal itself from being eroded by sea water
B、produce the waterproof super glue
C、protect itself from being blown away by strong wind
D、protect itself from being the food of other animals
答案D
解析 由题干A mussel grips a hard surface very firmly to 定位到原文第二段第四句When you try to move a mussel from a rock，you will discover what an incredibly firm grip it has-a necessity if the mussel is to resist the sharp grab of a hungry seabird or the pounding waves of the sea．细节题。注意此句破折号后面的解释：要防止"hungry seabird"和"pounding waves"，故答案为D)。[避错]A)“保护他们自己不被海水侵蚀”，虽然原文第二段"the pounding waves of the sea"谈到来自于海浪的冲击，但erode(指由于海水的生化作用导致的贝壳腐蚀)和pound(指由于海浪的连续冲击导致的贝壳破碎)有本质的区别，B)“制造防水的强力胶水”本句意思符合全文但和此题所问无关，C)“保护他们自己不被强风吹走”原文末谈到此问题。
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